Abraham Rutgers

The transcription factor IKAROS plays an important role in lymphocyte development, differentiation, and as a tumor suppressor. To date, >70 IKAROS germ line heterozygous variants have been reported in patients with primary immunodeficiency (PID)/inborn errors of immunity (IEI) and leukemia, and this number continues to grow. Germ line IKAROS loss- and gain-of-function mutations have been linked to immunodeficiency, immune dysregulation, and hematologic malignancies, with a broad spectrum of clinical manifestations. Routine next-generation sequencing approaches in patients with PID/IEI have facilitated the identification of IKAROS variants, including several cases with variants of uncertain significance (VUS). To determine the VUS’ functional behavior, we systematically generated constructs recapitulating those changes and tested IKAROS functions in vitro. We also conducted an in-depth examination of the C-terminal dimerization domain using alanine-scanning mutagenesis to identify amino acids critical for dimerization and other functions. This work provides a comprehensive description of the biologic impact of 81 previously unreported and/or untested IKAROS variants, including 33 patient-detected germ line VUS and 48 laboratory-generated mutations in the dimerization domain. Among them, 15 of the patient-detected variants, primarily mapping to IKAROS DNA-binding or dimerization domains, and at least 21 of the laboratory-generated mutations, impaired IKAROS function and could explain or result in human disease. VUS located in between IKAROS DNA binding and dimerization domains were less likely to be functionally deleterious. Of note, both positive and negative functional data herein generated can be relevant for patients carrying these IKAROS variants, helping to establish a diagnosis and guide treatment decisions.

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) encompasses three rare yet interrelated diseases: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EGPA). Despite increasing recognition, the diagnosis of AAV remains challenging, even in specialized medical centres, owing to its clinical heterogeneity, overlap with mimicking conditions, and the variable performance of ANCA testing. The assessment of a patient suspected of AAV requires a timely synthesis of symptoms, physical examination, laboratory tests, histopathology and imaging data to substantiate the diagnosis, exclude alternative diagnoses, assess disease activity and extent, and enable rapid initiation of appropriate therapies. Classification is similarly complex, and evolving classification systems are based on clinical phenotype, ANCA specificity or a combination of both, each with implications for disease monitoring, therapeutic decisions and trial design. Assessing disease severity and predicting prognosis are fundamental but complicated by the diverse patterns of organ involvement, relapsing–remitting course and co-morbidities. Although validated tools exist for measuring disease activity, organ damage and prognosis, many limitations remain, particularly in identifying smouldering disease, irreversible damage and risk of relapse. Emerging therapies have improved outcomes, with recovery of kidney function, better overall survival and improved glucocorticoid-related toxicity, but patients with AAV continue to experience high risks of chronic morbidity and early mortality. This Review explores current challenges and opportunities in the diagnosis, classification and prognostic assessment of AAV, and outlines a structured framework to support personalized and outcome-focused care.

Objectives: Nasal carriage of toxic shock syndrome toxin-1 (TSST-1)-positive Staphylococcus aureus (SA) is associated with a high relapse rate in granulomatosis with polyangiitis (GPA), suggesting TSST-1’s role in disease progression. This study investigated the immune response to S. aureus-derived TSST-1 and characterized TSST-1-specific Th cells in GPA patients. Methods: Plasma anti-TSST-1 IgG levels were measured in 45 remission GPA patients and 25 healthy controls (HCs) using ELISA. Circulating TSST-1-reactive CD4+T helper (Vβ2+Th) cells were analysed and sub-classified in 62 remission GPA patients and 22 HCs by flow cytometry. Additionally, PBMCs were stimulated in vitro with TSST-1 for 14 days to evaluate its effect on PR3-ANCA production and CD4+Th cell cytokine production (IFNγ, IL-4, IL-17, IL-21) measured by Phadia ImmunoCAP®250 and flow cytometry, respectively. Results: GPA patients with nasal SA carriage (SA+) had lower plasma anti-TSST-1 IgG levels and reduced numbers of circulating Vβ2+Th cells compared with HCs. An increased frequency of Vβ2+Th cells expressing the phenotype of peripheral helper T cells (TPh; PD-1HighCXCR5Neg) was observed in SA+ GPA patients compared with HCs. TSST-1 stimulation enhanced IL-21 production in Th cells from SA+ patients and induced PR3-ANCA production in vitro in a subset of GPA patients. Notably, numbers of circulating Vβ2+Th cells correlated positively with increased relapse-free survival in SA+ GPA patients. Conclusion: Impaired humoral immunity against Vβ2-restricted superantigens in SA+ GPA patients may lead to insufficient clearance of TSST-1. TSST-1-driven IL-21 production could enhance ANCA production and promote disease progression. Reduced Vβ2+Th cells may increase relapse risk, emphasizing their potential value as a tool for monitoring disease progression.

Objective: Vacuoles E1 enzyme X‐linked autoinflammatory somatic syndrome (VEXAS) is a recently identified rare genetic disorder associated with somatic mutations in the UBA1 gene. VEXAS presents with a combination of inflammatory and hematologic manifestations, leading to increased morbidity and mortality. Methods: Given the variability in disease presentation and the limited number of studies to date, no clinical documents currently exist to provide guidance to health care providers about the management of VEXAS. To address this gap, we formed an international multidisciplinary panel of VEXAS experts. Results: Through formalized meetings and a voting process, the group developed consensus clinical guidance considerations for the management of VEXAS. These considerations offer practical advice on several key topics: (1) clinical features of VEXAS, (2) UBA1 screening methods, (3) the diagnosis of myelodysplastic syndromes (MDSs) in patients with VEXAS, and (4) prognosis and management. The aim is to provide expert guidance on which patients to test, how to test for VEXAS, how to approach MDS in the context of VEXAS, and considerations for management. Conclusion: This work marks the first formal international consensus guidance for VEXAS and is intended to be used as a resource for clinicians seeking to understand the disease and its management.

Granulomatosis with polyangiitis (GPA) is a B-cell-mediated, relapsing, autoimmune disease. There is a need for novel therapeutic approaches and relapse markers to achieve durable remission. B cells express immune regulatory molecules that modulate their activation and maintain tolerance. While recent studies show dysregulation of these molecules in other autoimmune diseases, data on their expression in GPA are limited. This study aimed to map the expression of surface immune regulatory molecules on circulating B-cell subsets in GPA and correlate their expression with clinical parameters. Immune regulatory molecule expression on circulating B-cell subsets was comprehensively examined in active GPA (n = 16), GPA in remission (n = 16), and healthy controls (n = 16) cross-sectionally using a 35-color B-cell-specific spectral flow cytometry panel. Our supervised and unsupervised in-depth analysis revealed differential expression of inhibitory and stimulatory immune molecules on distinct B-cell populations in GPA, with the most notable differences observed in active GPA. These differences include the upregulation of FcγRIIB on nonmature B cells, downregulation of CD21 and upregulation of CD86 on antigen-experienced B cells, and elevated CD22 expression on various populations. Additionally, we found a strong association between FcγRIIB, BTLA, and CD21 expression on specific B-cell populations and disease activity in GPA. Together, these findings provide novel insights into the immune regulatory molecule expression profile of B cells in GPA and could potentially form the foundation for new therapeutic approaches and disease monitoring markers.

Purpose of review: (Levamisole adulterated) cocaine can cause a number of symptoms. One of the most severe is cocaine-induced vasculitis, which is hard to both diagnose and treat. We conducted a review to summarize the most recent findings on symptomatology, treatment options, anti-neutrophil cytoplasmic antibodies (ANCA) positivity and pathophysiology. Recent findings: In the past years multiple large cohort studies have been published extensively describing the symptomology and rates of ANCA positivity in patients with (levamisole-adulterated) cocaine-induced vasculitis. These studies also give more insight into the effects of different treatment strategies. Summary: The mainstay of treatment is abstinence of cocaine supported by antibiotics in case of concomitant infections and/or immunosuppressive medication depending on symptoms. ANCA positivity is a hallmark of more extensive disease and is a characteristic of immune system activation. In cocaine-induced vasculitis, dual positivity for both proteinase 3(PR3)- and myeloperoxidase (MPO)-ANCA is described and some patients are found to have human elastase type (HNE-)ANCA. HNE-ANCA positivity varies in patients with cocaine-induced midline destruction (CIMDL) from 28-84%, but has not been researched thoroughly in patients with cocaine-induced vasculitis. We present our hypothesis of a “sliding-scale” by which CIMDL turns into cocaine-induced systemic vasculitis based upon recent literature and we describe the mechanisms by which cocaine-induced vasculitis develops.

Background: Tumor-infiltrating immune cells have been correlated with prognosis for patients treated with immune checkpoint inhibitor (ICI) treatment of various cancers. However, no robust biomarker has been described to predict treatment response yet. We hypothesized that the activation potency of circulating T cells may predict response to ICI treatment. Methods: An exploratory analysis was conducted to investigate the association between the response to immune checkpoint inhibition (ICI) combined with stereotactic radiotherapy (SBRT) and the potency of circulating T cells to be activated. Blood-derived lymphocytes from 14 patients were stimulated ex vivo with, among others, Staphylococcal enterotoxin B (SEB) and compared to healthy controls (HCs). Patients were grouped into responders (>median progression free survival (PFS)) and non-responders (+ and CD8⁺ T cells in response to stimulation was measured using flow cytometry. In addition, serum levels of BAFF, IFNγ, and IL-2 receptor (sIL-2R) were measured by Luminex. Results: At baseline, a higher percentage of activated CD8⁺ T cells (15.8% vs. 3.5% (p = +CD69⁺CD8⁺ T cells (8.8% vs. 2.9% (p = 0.02)) was observed in responders compared to non-responders upon ex vivo stimulation with SEB. The concurrently measured serum cytokine levels were not different between responders and non-responders. Conclusion: Baseline blood CD8⁺ T cell activation potency, measured by intracellular cytokine production after ex vivo stimulation, is a potential biomarker to discriminate responders from non-responders to SBRT combined with ICI.

Kornelis S M van der Geest, Maria Sandovici, A Rutgers, Elisabeth Brouwer; Comment on: Immune checkpoint inhibitor-mediated polymyalgia rheumatica versus p

To compare clinical characteristics, imaging findings and treatment requirements of patients with immune checkpoint inhibitor-mediated polymyalgia rheumatica (ICI-PMR) and primary PMR. This single centre, retrospective cohort study compared ICI-PMR in patients with cancer (n = 15) to patients with primary PMR (n = 37). A comparison was made between clinical symptoms, laboratory markers, ultrasonography,¹⁸F-FDG-PET/CT findings and treatment requirements related to PMR. Patients with ICI-PMR less frequently fulfilled the EULAR/ACR classification criteria for PMR (66.7%) than patients with primary PMR (97.3%). Morning stiffness, weight loss and elevation of the ESR were less frequently seen in patients with ICI-PMR. No differences were observed regarding the presence of inflammatory lesions on ultrasound of the shoulders and hips between the two groups. The Leuven and the Leuven/Groningen ¹⁸F-FDG-PET/CT scores were significantly lower in the ICI-PMR group. Finally, the ICI-PMR group could be managed with less glucocorticoids than the primary PMR group. Our findings indicate that ICI-PMR may have a milder course with less inflammation than primary PMR on ¹⁸F-FDG-PET/CT. ICI-mediated PMR patients can be managed with a relatively low glucocorticoid dose. Our study underscores that ICI-PMR should be regarded as PMR-like syndrome.